The objective of this paper is to contrast random generators built by Redshaw and Robinson with simpler generators devised by the author. The test procedures laid down in an earlier paper are followed. Both types of random generator were designed for the simulation of random arrivals of vehicles at road-traffic intersections. There is, however, a wide variety of other applications for such generators. These include message-switching simulation, and the simulation of the operation of the central processor of a multiprogram computer. The tests performed indicated that both classes of generator satisfied criteria for randomness, provided that care was exercised at the design stage.